(1.) Field of the Invention
The present invention relates to an organic nonlinear optical material. More particularly, the present invention relates to a novel organic nonlinear optical material comprising a 4-nitrophenylaminoacetaldehyde acetal, and also to a novel organic nonlinear optical material comprising an acetalized polyvinyl alcohol having the above-mentioned substance as the side chain.
(2.) Description of the Prior Art
Since an organic nonlinear optical material has a large nonlinearity, it is expected that this material will be used as a base material of an optoelectronic device in the future.
For example, urea, 2-methyl-4-nitroaniline, 4-nitro-4'-methylbenzylideneaniline and 3-methyl-4-nitropyridine N-oxide are known as typical instances of the organic nonlinear optical material.
However, when these organic nonlinear optical materials are used as optical elements, the following serious problems should be solved.
(1) Most of the materials of the 4-nitroaniline series have a subliming property and have no dimensional stability.
(2) When a semiconductor laser is used as the light source, a nonlinear organic material should be used as an optical waveguide. The above-mentioned organic materials are, however, poor in the moldability and processability for the production of optical waveguides.
Furthermore, the above-mentioned organic materials involve a problem concerning electric field orientation.